At‐ten′u‐a″tion (�), n. [L. attenuatio: cf. F. atténuation.] 1. The act or process of making slender, or the state of being slender; emaciation.
2. The act of attenuating; the act of making thin or less dense, or of rarefying, as fluids or gases.
3. The process of weakening in intensity; diminution of virulence; as, the attenuation of virus.